The Federal Motor Carrier Safety Administration (FMCSA) has granted a five-year exemption allowing carriers operating Level 4 autonomous trucks to use cab-mounted warning beacons instead of traditional reflective warning triangles when their vehicles stop on the roadside. The exemption, signed by FMCSA Administrator Derek Barrs on Wednesday, remains in effect through October 7, 2031.
The decision covers Aurora Operations and extends eligibility to other carriers operating under comparable conditions, provided they notify the agency before adopting the alternative warning system.
The ruling replaces four consecutive three-month waivers that Aurora had operated under since October 2025. Kodiak AI, Waabi and Stack AV also joined the earlier waiver program.
For the autonomous trucking sector, the longer authorization provides greater regulatory certainty as companies expand operations, seek capital and establish commercial partnerships.
“Going from a temporary waiver to a five-year exemption gives the industry a lot of confidence,” said Jeff Farrah, CEO of the Autonomous Vehicle Industry Association, in an interview with FreightWaves. He explained that companies scaling their operations have repeatedly faced questions about how driverless trucks would comply with roadside warning requirements.
Bart Teeter, director of fleet and operational safety at Bot Auto, also welcomed the decision. In a statement, he said the exemption provides the autonomous freight industry with an important degree of regulatory certainty, enabling companies to continue expanding while maintaining safety.
Under existing federal rules, drivers whose trucks stop on a roadway or shoulder must activate their hazard warning lights and deploy warning devices within 10 minutes. The requirements call for three bidirectional reflective triangles or at least six fusees.
Autonomous vehicles present a practical challenge because no human operator may be available to leave the cab and position warning devices behind a disabled or stopped truck.
“With autonomous vehicles, we need to evolve some of these requirements, since with an autonomous truck there is not going to be somebody who can get out and put warning triangles behind the vehicle,” Farrah said.
Technical requirements and restrictions on autonomous truck operations
The exemption establishes specific technical standards and operational limits intended to ensure that cab-mounted beacons provide a reliable warning to other motorists.
The lights must emit amber light, comply with the Class 1 photometric requirements of SAE J595 and be installed at least 100 inches above the ground, at or above the height of the side mirrors.
Each vehicle must have at least three warning lights: one facing rearward on each side of the cab and one facing forward at the front. The system must also include redundant power to prevent a single-point electrical failure from disabling the warning equipment.
The beacons must activate within five minutes of the truck stopping and continue flashing alongside the vehicle’s standard hazard lights. They must remain active until the truck moves again or is recovered.
FMCSA described the five-minute activation requirement as “a clear, verifiable safety improvement” compared with the existing 10-minute period allowed for drivers to deploy reflective triangles.
The exemption also limits where and how autonomous trucks may operate. Vehicles must remain on roads within their validated operational design domain, the specific conditions and environments for which their autonomous driving systems have been validated.
Participating carriers are prohibited from transporting hazardous materials or passengers. They also cannot undertake operations that would require a human driver to hold an H, X, P or S commercial driver’s license endorsement.
Doubles are permitted only when configured with two 28-foot trailers. Triple-trailer combinations are prohibited, although tanker operations are allowed.
Before beginning operations under the exemption, every participating carrier other than Aurora must notify FMCSA by email and certify, under penalty of perjury, that its vehicles are equipped with the required beacons and will comply with all applicable conditions.
Carriers must report any crash occurring while the beacons are activated, or should have been activated, within five calendar days. Annual reports covering beacon malfunctions and power-related problems must be submitted by November 1.
The exemption also prevents states from enforcing conflicting requirements against interstate operations covered by the federal authorization.
Farrah emphasized that the exemption is not exclusive to Aurora, despite the company’s role in initiating the application and participating in the original waiver process.
“It is not just Aurora. It is any other autonomous vehicle company doing these operations,” he said.
From a 2024 rejection to a nationwide regulatory pathway
The five-year exemption follows an earlier setback for operators of self-driving vehicles.
In December 2024, FMCSA denied a 2023 petition from Aurora and Waymo for approval of alternative warning systems. The agency said at the time that allowing an exemption for an undefined group of carriers with unspecified equipment and vehicles would undermine the need to show that they are operating at an equivalent level of safety.
The new authorization resolves these concerns by identifying the equipment that will be required, specifying the vehicles and operating conditions to be covered, and requiring the carriers that would participate to identify themselves to the agency.
After rejecting Aurora, the FMCSA granted it a more limited waiver.
Aurora has operated 34 trucks with the warning beacons from Oct. 10, 2025 through Jan. 9, 2026, and has driven over 500,000 miles, according to the company’s application. During the reported period, the beacons were operational for nearly 10 hours.
Aurora reported no faults, no malfunctions or power related problems. FMCSA said that none of the trucks had been in a collision while stopped with the beacons on.
Aurora in April filed its application for the five-year exemption and proposed operational restrictions similar to those under the temporary waiver.
The agency also reexamined two studies provided as part of the applications.
FMCSA had incorporated findings from Aurora’s October 2022 Naturalistic Study of Warning Device Equivalency into its 2024 review. Drivers responded to warning beacons in five out of eight scenarios at a slightly lower rate than reflective triangles, the study found.
FMCSA also considered how far away motorists started taking evasive action in the most recent ruling. The same study found that drivers initiated evasive maneuvers an average of 135.71 meters from the beacons versus 133.24 meters from reflective triangles.
A separate study by the Virginia Tech Transportation Institute for Waymo found in August 2022 that warning beacons triggered earlier braking at nite.
These findings together were part of the evidence considered by the agency in deciding if the alternative system could meet an acceptable level of safety.
402 public comments on deep split over roadside safety
Reflective triangles should be replaced by cab-mounted lights on self-driving trucks, but not, the public has shown in a deep divide with 402 comments on Aurora’s application.
They were opposed by the Owner-Operator Independent Drivers Association, or OOIDA, the Truck Safety Coalition, Advocates for Highway and Auto Safety, REAL Women in Trucking and many individual truck drivers.
Backers included Amazon and the National Fraternal Order of Police, but also the American Trucking Associations, Waymo, Kodiak AI and Volvo Group North America.
Critics were concerned about the visibility and reliability of the proposed system in real-world conditions. One major concern was that a jackknifed truck or a trailer that was at an angle could block the warning lights on the cab, making them less effective for oncoming drivers.
Others cautioned that with redundant power systems required, one electrical failure could take out the beacons. Commentors also questioned whether existing research fully accounted for the variety of weather, road and lighting conditions faced by commercial trucks.
Some opponents said that 10 hours of beacon use during planned stops was not enough evidence to approve a five-year exemption.
The Small Business in Transportation Coalition said the decision “would open a can of worms” by allowing driverless trucks to run with lighter requirements than are imposed on vehicles with human drivers.
OOIDA also told FMCSA to wait for the agency to finish its own study on warning devices for stopped commercial motor vehicles before it makes its decision.
The FMCSA defended the exemption by referring to operational constraints that confine the participating trucks to their validated operating environments. The agency also has no data showing reflective triangles have a significant impact on driver reaction time.
The agency also noted that whether warning devices like this improve traffic safety in general is still a question that has been historically unanswered definitively.
The discussion went beyond autonomous trucks. The Autonomous Vehicle Industry Association and Volvo also asked FMCSA to consider allowing cab-mounted beacons on conventional commercial vehicles, as well.
The agency conceded it “may be ripe for future regulatory action” to change warning-device requirements for the larger commercial vehicle industry. That leaves the door open for broader changes to federal roadside safety rules.
Industry sees beacons as a key step toward autonomous freight expansion
Aurora welcomed the exemption as a development that could improve roadside safety while addressing a practical limitation of driverless trucking.
“High-visibility, cab-mounted warning beacons are a critical, 21st-century solution that enhances roadside safety by immediately alerting other road users without ever needing to put a person in harm’s way,” said Gerardo Interiano, Aurora’s senior vice president of government relations and public affairs, in a statement.
According to Farrah, the autonomous vehicle industry has increasingly converged around cab-mounted warning beacons, an approach initially developed by Waymo and Aurora.
The five-year authorization provides a clearer framework for companies seeking to expand autonomous freight operations in the United States. It also establishes conditions under which other qualifying carriers can adopt the technology without relying on successive short-term waivers.
“This is a critical step, because this is one of the issues that has been really problematic for the deployment of autonomous trucks,” Farrah said. “Now we have a pathway to deploying in the U.S.”
The decision resolves an important regulatory obstacle for Level 4 autonomous trucking, although concerns over equipment reliability, visibility and the adequacy of the supporting safety evidence remain central to the broader debate over driverless freight operations.
